This method takes any Perl value as its only argument, and dispatches to the
various other visiting methods using visit_no_rec_check, based on the datas
If the value is a reference and has already been seen then visit_seen is called.
|visit_seen $data, $first_result||
When an already seen value is encountered again its typically replaced with
the result of the first visitation of that value. The value and the result of
the first visitation are passed as arguments.
Called for any value that has not yet been seen. Does the actual type based
dispatch for visit.
Should not be called directly unless forcing a circular structure to be unfolded. Use with caution as this may cause infinite recursion.
|visit_object $object||If the value is a blessed object, visit calls this method. The base implementation will just forward to visit_value.|
Generic recursive visitor. All non blessed values are given to this.
visit_object can delegate to this method in order to visit the object anyway.
|visit_scalar $scalar_ref||These methods are called for the corresponding container type.|
|visit_value $value||If the value is anything else, this method is called. The base implementation will return $value.|
|visit_hash_entry $key, $value, $hash||Delegates to visit_hash_key and visit_hash_value. The value is passed as $_ so that it is aliased.|
|visit_hash_key $key, $value, $hash||Calls visit on the key and returns it.|
|visit_hash_value $value, $key, $hash||The value will be aliased (passed as $_).|
|visit_array_entry $value, $index, $array||Delegates to visit on value. The value is passed as $_ to retain aliasing.|
|visit_tied $object, $var||
When tied_as_objects is enabled and a tied variable (hash, array, glob or
scalar) is encountered this method will be called on the tied object. If a
valid mapped value is returned, the newly constructed result container will be
tied to the return value and no iteration of the contents of the data will be
made (since all storage is delegated to the tied object).
If a non blessed value is returned from visit_tied then the structure will be iterated normally, and the result container will not be tied at all.
This is because tying to the same class and performing the tie operations will not yield the same results in many cases.
|retain_magic $orig, $copy||
Copies over magic from $orig to $copy.
Currently only handles bless. In the future this might be expanded using Variable::Magic but it isnt clear what the correct semantics for magic copying should be.
|trace||Called if the DEBUG constant is set with a trace message.|
This object can be used as an fmap of sorts - providing an ad-hoc functor interface for Perl data structures.
In void context this functionality is ignored, but in any other context the default methods will all try to return a value of similar structure, with its children also fmapped.
Data::Visitor is a Moose class, so it should be subclassed using Moose.
Then override the callback methods in any way you like. To retain visitor behavior, make sure to retain the functionality of visit_array and visit_hash.
o Add support for natural visiting of trees. o Expand retain_magic to support tying at the very least, or even more with Variable::Magic if possible.
Data::Rmap, Tree::Simple::VisitorFactory, Data::Traverse
o Yuval Kogman <firstname.lastname@example.org> o Marcel Gruenauer <email@example.com>
This software is copyright (c) 2013 by Yuval Kogman.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.
|perl v5.20.3||DATA::VISITOR (3)||2013-06-24|